Context.Reference<LogLevel>Context reference for setting the minimum trace level threshold. Spans and their descendants below this level will have their sampling decision forced to false, preventing them from being exported.
When to use
Use to set the trace-level threshold that controls whether spans are sampled by default.
Details
The default value is "All". Span creation compares the span level from
options.level ?? CurrentTraceLevel against this threshold.
Gotchas
Explicit options.sampled bypasses threshold computation.
export const const MinimumTraceLevel: Context.Reference<LogLevel>const MinimumTraceLevel: {
defaultValue: () => Shape;
of: (this: void, self: LogLevel) => LogLevel;
context: (self: LogLevel) => Context.Context<never>;
use: (f: (service: LogLevel) => Effect<A, E, R>) => Effect<A, E, R>;
useSync: (f: (service: LogLevel) => A) => Effect<A, never, never>;
Identifier: Identifier;
Service: Shape;
key: string;
stack: string | undefined;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
Context reference for setting the minimum trace level threshold. Spans and their
descendants below this level will have their sampling decision forced to
false, preventing them from being exported.
When to use
Use to set the trace-level threshold that controls whether spans are sampled
by default.
Details
The default value is "All". Span creation compares the span level from
options.level ?? CurrentTraceLevel against this threshold.
Gotchas
Explicit options.sampled bypasses threshold computation.
MinimumTraceLevel = import ContextContext.const Reference: <Service>(
key: string,
options: {
readonly defaultValue: () => Service
}
) => Reference<Service>
Creates a context key with a default value.
When to use
Use when you need to define a context key with a lazily computed default
value.
Details
Context.Reference allows you to create a key that can hold a value. You
can provide a default value for the service, which will automatically be used
when the context is accessed, or override it with a custom implementation
when needed. The default value is computed lazily and cached on the
reference.
Example (Creating references with default values)
import { Context } from "effect"
// Create a reference with a default value
const LoggerRef = Context.Reference("Logger", {
defaultValue: () => ({ log: (msg: string) => console.log(msg) })
})
// The reference provides the default value when accessed from an empty context
const context = Context.empty()
const logger = Context.get(context, LoggerRef)
// You can also override the default value
const customContext = Context.make(LoggerRef, {
log: (msg: string) => `Custom: ${msg}`
})
const customLogger = Context.get(customContext, LoggerRef)
Reference<
type LogLevel = "All" | "Fatal" | "Error" | "Warn" | "Info" | "Debug" | "Trace" | "None"Represents every level used by Effect logging, including concrete message
severities and the All and None sentinel levels.
When to use
Use to type values that may be either concrete log message severities or
logging configuration sentinels.
Details
The levels are ordered from most severe to least severe:
All - Special level that allows all messagesFatal - System is unusable, immediate attention requiredError - Error conditions that should be investigatedWarn - Warning conditions that may indicate problemsInfo - Informational messages about normal operationDebug - Debug information useful during developmentTrace - Very detailed trace informationNone - Special level that suppresses all messages
Example (Using log levels)
import { Effect } from "effect"
// Using log levels with Effect logging
const program = Effect.gen(function*() {
yield* Effect.logFatal("System failure")
yield* Effect.logError("Database error")
yield* Effect.logWarning("High memory usage")
yield* Effect.logInfo("User logged in")
yield* Effect.logDebug("Processing request")
yield* Effect.logTrace("Variable state")
})
// Type-safe log level variables
const errorLevel = "Error" // LogLevel
const debugLevel = "Debug" // LogLevel
LogLevel
>("effect/Tracer/MinimumTraceLevel", { defaultValue: () => LogLeveldefaultValue: () => "All" })